Technical Field
The invention relates to a wind turbine with optical pressure sensors and to a method for operating such a wind turbine.
Description of the Related Art
According to the prior art, wind turbines are exposed to winds with different properties which in particular strike the rotor blades of the wind turbine from different directions and with different strengths. With these different wind conditions, the wind turbines convert kinetic energy which is extracted from the wind into electrical energy and feeds the latter into a supply grid. When converting the wind energy into electrical energy, the wind turbine is operated, depending on the wind conditions and a predetermined electrical output which needs to be fed in, at different operating points, wherein each operating point is determined in particular by a blade pitch angle and a generator torque to be set.
The operating point is hereby set as ideally as possible in order to enable efficient operation whilst considering a long service life and increasingly also whilst respecting low levels of operating noise. Efficient means, in particular, generating as much energy as possible from the available wind. Operating noise, which is caused especially by turbulence at the rotor blades, hereby needs to be minimized in particular when the wind turbine is erected in the vicinity of residential areas so that the residents are not disturbed by the noise of the rotor blades of the wind turbine.
In order to meet the said requirements for operation, rotor blades are usually developed and simulated with the aid of a computer, wherein the actual behavior of the rotor blades thus developed is also verified using models in practical trials in a wind tunnel. During development, the rotor blades are, for example, developed so that they are adapted to the wind conditions prevailing at the erection site.
The control devices and/or regulating devices of a wind turbine, which set and/or regulate the ideal operating point of the turbine, are accordingly adapted to the properties of the respective rotor blade. To do this, a type of rotor blade model, which in the most simple case consists of one or more conversion tables, is saved in the control device and/or the regulating devices. Using the rotor blade model and taking into account the measured wind conditions, an operating point is then set and/or regulated so that an estimated situation of airflow onto the rotor blade is achieved. The phrase situation of airflow is here in particular understood in particular to be the pattern of airflow at the rotor blade.
The control devices and/or regulating devices of a wind turbine accordingly take into account the predetermined behavior of each rotor blade installed on the wind turbine in order to set the operating points of the wind turbine. However, the problem arises with this type of regulation and/or control that the behavior of the rotor blades changes in the course of their service life and as a result the operating point can no longer be set ideally solely by taking into account the predetermined rotor blade model.
Moreover, such an ageing process of the rotor blades can also not be taken into account in the rotor blade model because it is dependent on multiple factors which are also random. Thus, for example, erosion, namely in particular layers of paint becoming detached from the rotor blade, which occurs at the leading edges of the rotor blade, in particular in the outer region of the rotor blades, has a major influence on the flow behavior at the rotor blade surface or the rotor blade wall. Erosion is, however, in particular dependent on the quantity and quality of particles in the surrounding air of the respective wind turbine so that erosion which occurs cannot be predicted.
Accordingly, the predetermined situation of airflow onto the rotor blades in the regulated and/or set operating points after operating for a certain period of time no longer corresponds to the actual situation of airflow.
The German Patent and Trademark Office has conducted a search in the priority application and found the following prior art: WO 2012/122 669 A1 and U.S. Pat. No. 7,159,468 B2.